Sloped Roofs: Wind Load Cases

[Stazz]

Risa floor doesn't seem to include the wind load cases into the load combinations. I tried a few things to bypass this shortcoming when I wanted to apply a Wind Load to the sloped roof of a Risa Floor model.

1)I put the wind load in as an OL1 surface load in the "y" direction and then added the appropriate load combinations.

This didn't work because the joists designs don't consider the OL's in the design.

2) I applied the wind load as a tapered load (with the same max and min values) and put the load in the RL (Rain) load case. Then I altered the load combination so that RL had the wind load factors.

This didn't work because I couldn't apply the RL load case in the "y" (local y-axis) direction which is the direction wind load is applied to sloped beams.

3) I thought about trying idea (2) along with increasing the load by Load/cos(roof angle) so that when the load gets resolved the correct wind load will act perpendicular to the member.

This wont work because axial wind loads will enter the joists which isn't true.


Does anyone have any other ideas? Is Risa thinking of adding a Wind Load case soon?

 

[JoshPlumSE]

Since RISAFloor is really designed purely for vertical loads, there is not currently a wind load category.

However, we do provide the OL1~OL9 load cases if you need to define a vertical wind or seismic as part of the vertical load solution. Therefore, your solution (1) was really what we had in mind for this type of load. Unfortunately, the design of open web SJI type joists for up-lift is beyond the design capabilities of the program. Therefore, you can still get moment and shear diagrams and such. But, you will have to use these to design your bridging of these joists by hand.

Josh